According to [1] it breaks down like this:

EV at rapid/ultra-rapid chargers: 25p/mile

Petrol, diesel: 15p/mile

EV charging at home: 8p/mile

This is because there's a government price cap on home electricity, but not on commercial electricity - and rapid chargers are all commercial (and of course for-profit).

[1] https://www.rac.co.uk/drive/electric-cars/charging/electric-...